Determine whether each table in Exercises 11–16 is a probability model. If not, clearly explain why it is not a probability model.
15. Students taking undergraduate introductory statistics
| Class | Probability |
|---|---|
| Freshmen | 0.15 |
| Sophomores | 0.25 |
| Juniors | 0.40 |
| Seniors | 0.20 |
5.1.15
Probability model.